This dissertation is a longitudinal research study examining the traits of CEOs over thirty years to determine whether the labor market for CEOs has changed over time. This projects adopts an Institutional Theory perspective to predict whether the field of chief executives has become more professional, or occupational, over time, and whether the traits of CEOs have become more similar as predicted by institutional isomorphism. Lastly, organizational and industrial variables were included to see if they could help predict what kind of CEO would be hired. Quantitative and qualitative analyses were used in this study. This study documents traits of new CEOs have changed over time. Looking at nine variables, including ages at which individuals became CEOs, educational level, number of previous employers, organizational tenure, and five others, all the traits changed significantly over the course of the study. There was also support for the idea that CEO careers increasingly reflected occupational labor market rather than internal labor markets, which suggests the field of business management is becoming more of a profession. Over time, CEOs were apt to have had more previous employers, they were increasingly older when they joined their organization, and they joined their organizations at positions of higher status. There was no empirical support CEOs had become more similar to each other, or isomorphic, as predicted by institution theory. Instead, the qualitative evidence suggests that CEOs have always been a homogeneous bunch. As a result, any increases similarity would be difficult to observe. When organizational and industry variables were included, only one, organizational age, was able to predict what kind of CEO would be hired. The results of this research argue that CEOs have been an elite group and continue to be so. Even though their traits have changed, they have not changed enough to include individuals from outside their general demographic boundaries.